Automatic crane grab



Jue .12, 1928.

F. GERDES AUTOMATIG CRANE G n-A Filed Dec. 2, v1926 4'Sheetsf-Sh'e'et lFig. z

F. GERDES AUTOMATIC CRANE GRAB June 12, 1928.y

Filed Deo. 2. 192e 4 sheets-sheet v 2 /nventbm .,Lw

`lune 12, 1928.

F. GERDEs AUTOMATIC CRANE GRAB Filed Dec. 2, 1926 4 Sheets-SheetIIIIIIIIIIIIIIIII /n Vento/z' June 12, 1928. y 1,673,237

F. GERDEs AUTOMATIC CRANE GRAB Filed Dec. 2, 1926 4 Sheets-Sheet 4/nventm Patented June 1 2, 192s.

y AUNITED' STATES PATENT OFFICE."

FRANZ GERDES, OF ESSEN-EUHR, GERMANY.

AUTOMATICCRANE GRAB.

Application filed December 2, 1926, vSerial No. 152,261, and in GermanyJanuary l9, 1926.

The invention relates to an automatic crane grab or gripping device foruse either on loads which are enclosed in a container ora on singlepiece loads. Two constructional examples embodying a similar principleare illustrated by way of example in the drawings in which Fig. 1 is anelevation, partly in section, illustrating one embodiment of theinvention.

2 is an lenlarged detail elevation of the movable ram and itsassociatedparts.

Fig. 8 is a side elevation of the const-ruction shown in Fig. 2.

Fig. 4 is an enlarged elevation of a modification of the invention.

Fig. 5 -is a vertical sectional view taken at right .angles to Fig. 4. Y

' Figs. 6 and 7 are respectively a side elevation and a front elevationof the slide and arresting levers carried therewith.

Fig. 8 is a detail elevation showing the arresting levers carried bytheslide (Figs. G and 7) in their open position.

The grab in accordance with Figs. 1-3 lifts containers or any singlepiece loads which are capable of being gripped either'V underneath or bymeans of projections or otherwise. The grab or gripping device inaccordance with Figs. 48 is of tong-like form.

lt is truc that semi-automatic tong-grabsl are known in which theopening and locking of the arms of the tongs take place ondepositing thetongs oii the load to be lifted. lVith such tong-grabs, however. someadditional assistance is necessary for the purpose. of suspending andplacing the load in them. In contra-distinction thereto the new grippingdevice in accordance with the present invention is entirely automaticand is characterized by its capabilityof standing, the centralarrangement of the arm-lock and a separate locking device in its head.The new grab' or gripping device is there foresuitable not only for workat places where the load is easily accessible but valso as a so-calleddipping grab for situations which are not in full view and are diiiicultof access by an attendant on account of heat, wet, steam, gas and thelike. The extreme certainty with which the new grab meets the load isdue to special precautionary means which almost entirely prevent thegrab from swinging about its axis of suspension. l

Referring to Figs. 1-3, of the drawings, the gripping device or grabconsists essentially of a frame-like body portion 1 in the middleofwhich is carried an upwardly and downwardly movable ram 2 having a plate3. The ram has a longitudinai slot 4 extending through it and isprovided at the side with a pawl 5 for actuating the mechanism. Thebearings 6 carry a shaft 7 which kpasses through the longitudinal slot 4in the rain 2, A star wheel Sand beside it a cam 9, for example ofelliptical shape,` are fixed on the shaft 7. Canis of other shapes thetwo diameters of which are of different length may also be employed,their object being toenable diilerent distances apart'to be obtained forreversing purposes. -In order to avoid jamming a symmetrical ellipticalcam 10 is also fitted on the opposite side of the ram 2. A bridge 11guided by the ram 2 rests on the edges of the two elliptical cams and isconnected by means of the. levers 12, 13 and 14 to the grab-claws 15fittedy on the frame 1. At the head 44 of the frame or body portion 1there is provided a suspension eye 16 which is laterally displaceableand in its position of rest lies approximately horizontal and of whichthe lower portions of the parts sur/ rounding the bolt holes are curvedout somewhat elliptically so that, when the eye '16 is upright, theypress against the shorter arms of the angle levers 18 but, when the. eye16 is displaced. theyvallow the shorter arms of the levers 18 to flyupwards. These serve the purpose of automatically adiusting the closuiecheeks which clamp the block 42 of the tackle of the crane in order thatthe grab suspended from the hook 43 cannot k.at any time rotaterelatively to the block 42.

The method of operation of this form of construction of the invention isas followsQ Atv the beginning ofthe operation the operator of the craneslips the hook 43 of the crane intothe suspension eye y16 and hoists,whereupon the two cheeks 18 close automat-ically and'press closelyagainst the pulleyblock 42. -Rotation of the gripping device about theaxis of suspension is thereby avoided and a so-called semi-rigidity isobtained without any guides. After the grab has encounteredthe load andon beingfur ther lowered the ram- 2 is pushed upwards v,

into the frame 1.V The pawl 5 rotates the star wheel 8 and with it theelliptical cams 9 and 1 0 about an angle of approximately 90. Duringthis movement the bridge 11 slides over the periphery .of vtheelliptical cams until itis supported on their longerdiameter and hasclosed the grab-claws 15 vby means .of the levers 12,13 and 14, whichtakes place underthe influence ofthe weight ofthe grab itself. Vhile theload is being hoisted the ram I2 together with' the: plate 3 slidesbackwards into its. former position andthe pawl4 5 travelling therewithplaces itself ina position in which it is ready to engage the next,toothot lthe star wheel 8. lhen the load is set down the grab is againlowered on to it. The ram 2 and the pawl 5 again rotate the ellipticalcam about au auglle of 90 so that the bridge-11 is lowered on to ,theshorter diameter of the ellipse and thereby allows the claws to moveoutward. The centre inthe frame 1 about which the latter rotate ma bcvaried as desired as may be necessitated y 'the' size of the load at thetime, F urther, the elliptical curve may be 'connected by means'oftransverse bolts 24,

and 29. The shaft 25 is journalledA in the side plates 23"and carriestwo cams 26 which are connected with star wheels 27. In the middle ofthe grab .is located the ram 28 which is guided by the 'transverse bolts24 ries a and 29 and-.by the shaft 25, forwhich purpose the ram 28 isprovided with longitudinal slots 30 and 31. It is therefore movableupwards and'downwards. The ram -28 carpawl 32 on either-side 'fordriving the star w eels 27. The transverse bolt 24carries two arrestingmembers 33 for the position of rest of the grab. Two arresting levers 34which'are hinged to the^ slide 22 and are formed as lhooks at theirlower ends rest against the cams 26. On the front of the grab (Fig. 5)there is fitted the adjustment disc' 36 the object of which is to securethe mechanism of the cams against undesired movement with the aid of theleaf springs 37. A construct-ion of the adjusting disc 36 as a kind ofdouble indicator enables the position of rest or the gripping positionof the grab to-be easily recognized. Rollers or-wheels 38 facilitate theforward movement of the grab along the groundor on rails. At the head35-ot` the slideI 22 there is fitted a displaceable suspension eye 39and hinges 40- together withl the closure cheeks 41.

, The method ot operation of this form of ameter is vertical.

.mechanism must be.A in its position of rest which corresponds to that`ac ljustment'of the elliptical cams 26 in-whicli` theirloliger di.-

In this position the hooks at thelower ends of the arresting lcvers 34engage the carrying bolt of the arresting member 33 -for the purpose oflifting. `The operator of the crane allows' the hook 43 of the crane toslip into the suspension eye 39 and hoists. The checks 4l close againstthe block 42 and the hooks of the arresting levers 34 engage under thecarrying bolt whereby the grab is held open. On lowering the grab on toIthe load to be gripped the ram 28 is pushed upwards and 'its pawl32rotates the star wheel 27 and the cams 26 through an angle of 90.During this the arresting levers 34 are spread apart by fthe cams- 26,the carrying bolts ofthe arresting members 33 are thereby freed and theposition of rest is dissolved. The .op-

erator of the crane now hoists and the pair of jaws 19 closes and gripsthe load. During the lifting the ram 28 again slidesdownwards and thepawl 32' places itself iin posi-v tion to engage in front-.oftheneixt'tooth of the star-wheel 27. Onsetting down the .load the grab isagain completely set downen the load. The ram 28 and thev pawl 32 agamrotate the cams 26 about an angle of 90, andA the arresting levers 34again support themselves against the shorter elliptical axes of the cams26. Thefhooks of -the arresting levers 34 again slide. Under thecarrying bolts of the arresting member' 33l so that .the grab againreturns to the position of rest.

If, `after the operation is complete',-the grab is brought to itsstation, the closure cheeks 41 are opened yby a side thrust on thesuspension eye 39 and release the hook 43 of4 the craneso that it isfree to be removed. Y Iclaim:- i

1. An automatic grab "for cranes comprising a main body member, a pairof grab claws pivoted thereto, a ram shdably mounted on said bodymember, a pawl carried by said Tam, a bridge linked between said claws,and means interposed between sald bridge and body member and actuated bysaidpawlfor controlling the operation ot' lsaid claws.

2. An automatic grab for cranesvcompris- -ing a-main body member, a pairof grab claws pivoted thereto, a ram slidably'mountled. on said'bodymember, a pawl pivoted' on said uram, a bridge and link connectionbetween said claws, and a cooperating star wheel and cam mechanisminterposed be- FRANZ GERDES.

